Methods for regulating gas turbine engine fluid flow

ABSTRACT

A method enables a gas turbine engine to be operated. The method includes directing fluid flow from a source into an inlet of a valve, channeling the fluid flow entering an inlet portion of the valve towards an outlet portion of the valve such that a direction of the fluid flow is changed within the inlet portion, and controlling the amount of fluid flow entering the outlet portion of the valve by selectively positioning a valve disk coupled within the inlet portion of the valve by a valve disk axle. The method also comprises channeling the fluid flow from the inlet portion of the valve through the outlet portion of the valve and into a fluid supply pipe, wherein the valve outlet portion has a substantially right cylindrical shape such that a direction of fluid entering the body outlet portion remains substantially constant therethrough.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.10/272,799, filed Oct. 17, 2002 now U.S. Pat No. 6,755,990, which ishereby incorporated by reference and is assigned to assignee of thepresent invention.

BACKGROUND OF THE INVENTION

This invention relates generally to gas turbine engines and moreparticularly, to valve assemblies used to regulate fluid flow for a gasturbine engine.

Gas turbine engines typically include an engine casing that extendscircumferentially around a compressor, and a turbine including a rotorassembly and a stator assembly. Within at least some known engines, aplurality of ducting and valves coupled to an exterior surface of thecasing are used to channel fluid flow from one area of the engine foruse within another area of the engine. For example, such ducting andvalves may form a portion of an environmental control system (ECS).

At least some known valve assemblies are used to control fluid flow thatis at a high temperature and/or high pressure. Such valve assembliesinclude a substantially cylindrical valve body that is coupled betweenadjacent sections of ducting. The valve body includes a valve sealingmechanism that is selectively positionable to control fluid flow throughthe valve. More specifically, at least some known valves includes apiston/cylinder arrangement that is positioned external to the valvebody and is coupled to the valve sealing mechanism to provide the motiveforce necessary to selectively position the valve sealing mechanism.

Because the piston/cylinder arrangement is offset from the main valvebody, a center of gravity of the valve assembly is typically displaced adistance from a centerline axis of the valve body. Such an eccentriccenter of gravity may induce bending stresses into the valve assembly,adjoining tubing, and supporting brackets during engine operation.Depending on the application, the physical size and weight of thepiston/cylinder arrangement may also present difficulties during theduct routing phase of the engine design.

BRIEF SUMMARY OF THE INVENTION

In one aspect, a method for operating a gas turbine engine is provided.The method comprises directing fluid flow from a source into an inlet ofa valve, channeling the fluid flow entering an inlet portion of thevalve towards an outlet portion of the valve such that a direction ofthe fluid flow is changed within the inlet portion, and controlling theamount of fluid flow entering the outlet portion of the valve byselectively positioning a valve disk coupled within the inlet portion ofthe valve by a valve disk axle. The method also comprises channeling thefluid flow from the inlet portion of the valve through the outletportion of the valve and into a fluid supply pipe, wherein the valveoutlet portion has a substantially right cylindrical shape such that adirection of fluid entering the body outlet portion remainssubstantially constant therethrough.

In another aspect of the invention, a valve for use with a gas turbineengine is provided. The valve comprises a valve body including a valveinlet portion and an outlet portion. The inlet portion extends from aninlet to the body outlet portion. The body outlet portion forms asubstantially right cylinder that extends from the inlet portion to avalve outlet, such that a direction of fluid flowing within the bodyoutlet portion remains substantially unchanged between the body inletportion and the valve outlet. The inlet portion includes a valve diskand at least one bend formed between the body outlet portion and thevalve inlet such that a direction of fluid entering the valve bodythrough the valve inlet is changed prior to entering the body outletportion. The valve disk is pivotally coupled within the inlet portionfor controlling fluid flow through the valve.

In a further aspect, a gas turbine engine is provided. The engineincludes a fluid supply pipe a valve configured to regulate an amount offluid flow entering the fluid supply pipe. The valve includes a valvebody comprising an inlet, an outlet, an inlet portion, and an outletportion. The inlet portion extends between the inlet and the outlet. Theoutlet portion extends between the inlet portion and the outlet. Theoutlet portion has a substantially right cylindrical shape such that adirection of fluid entering the body outlet portion remainssubstantially constant therethrough. The inlet portion includes a valvedisk and at least one bend formed between the inlet and the body outletportion, such that a direction of fluid flowing through the body inletportion is changed prior to entering the outlet portion. The valve diskis used to control fluid flow through the valve into the fluid supplypipe.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a gas turbine engine including a plurality ofducting coupled together by a plurality of valve assemblies;

FIG. 2 is a cross-sectional view of one of the valve assemblies shown inFIG. 1;

FIG. 3 is an exploded perspective view of the valve assembly shown inFIG. 2;

FIG. 4 is a perspective view of an alternative embodiment of a valveassembly that may be used with the gas turbine engine shown in FIG. 1;and

FIG. 5 is a side view of the valve assembly shown in FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a side view of a gas turbine engine 10 including a pluralityof ducting 12 coupled together by a plurality of valve assemblies 14.Engine 10 includes a high-pressure compressor assembly 16, a combustor18, and a turbine assembly 20. In one embodiment, compressor 16 is ahigh-pressure compressor. Engine 10 also includes a low-pressure turbine(not shown) and a fan assembly (not shown). In one embodiment, engine 10is a CF34 engine commercially available from General Electric Company,Cincinnati, Ohio.

In the exemplary embodiment, ducting 12 and valve assemblies 14 form aportion of an engine build up (EBU) 30. More specifically, ducting 12and valve assemblies 14 facilitate channeling and controlling,respectively, fluid flow at a high temperature, and/or at a highpressure, from one area of engine 10 for use in another area. Forexample, in one embodiment, fluid flowing through ducting 12 and valveassemblies 14 has an operating temperature that is greater than 1000° F.and/or an operating pressure of greater than 300 psi.

In the exemplary embodiment, ducting 12 includes a Y-duct 32 thatfacilitates splitting EBU 30 into a pair of inlet duct assemblies 34 and36 that are coupled to an engine casing 40 by a plurality of mountingbracket assemblies 42. More specifically, inlet duct assemblies 34 and36 are coupled in flow communication to compressor 18 for routing bleedair from compressor 18 for use in other areas, such as an environmentalcontrol system.

FIG. 2 is a cross-sectional view a valve assembly 14. FIG. 3 is anexploded perspective view of valve assembly 14. Valve assembly 14includes a valve body 50 having a first body portion 52 and anintegrally-formed second body portion 54. In the exemplary embodiment,first body portion 52 is an inlet body portion, and second body portion54 is an outlet body portion, and both will be described herein as such.In an alternative embodiment, first body portion 52 is an outlet bodyportion, and second body portion 54 is an inlet body portion. Inletportion 52 extends from an assembly first end 56 to outlet portion 54,and outlet portion 54 extends from inlet portion 52 to an assemblysecond end 60. In the exemplary embodiment, assembly first end 56 is anassembly inlet, and assembly second end 60 is an outlet, and both willbe described herein as such. In an alternative embodiment, assemblyfirst end 56 is an assembly outlet for discharging fluids therefrom, andassembly second end 60 is an assembly inlet for receiving fluidstherein. Valve assembly 14 is hollow and includes a bore 64 that extendsbetween assembly inlet 56 and assembly outlet 60. Valve assembly 14 alsoincludes an exterior surface 66 that extends over inlet and outletportions 52 and 54, respectively.

Valve assembly outlet portion 54 includes an interior surface 70 and acenterline 72. Interior surface 70 extends through outlet portion 54 tooutlet 60 and defines a portion of assembly bore 64. Because outletportion 54 is a right cylinder, assembly outlet 60 is substantiallyperpendicular to outlet portion centerline 72.

Outlet portion 54 also includes an integrally-formed mounting flange 76,an inner shoulder 78, and a pair of actuator system connector linkmounts 80. Flange 76 extends circumferentially from outlet portionexterior surface 66 around assembly outlet 60, and includes a pluralityof openings 84. Openings 84 are each sized to receive a fastener 86therethrough for coupling outlet portion 54 to a valve-inner cylinder90.

Outlet portion shoulder 78 is positioned between flange 76 and actuatorsystem mounts 80. More specifically, a diameter d₁ of bore 64 withinoutlet portion 54, defined by surface 70, is substantially constantbetween assembly outlet 60 and shoulder 78, and is larger than adiameter d₂ of outlet portion bore 64 extending between shoulder 78 andinlet portion 52.

Valve-inner cylinder 90 is a substantially right hollow cylinder thatthat extends from an inlet edge 94 to an outlet edge 96, and includes anexterior surface 98 and an interior surface 100. Exterior and interiorsurfaces 98 and 100, respectively, define respective external andinternal diameters d₃ and d₄ for cylinder 90. Diameters d₃ and d₄ aresubstantially constant along cylinder 90 between edges 94 and 96, andboth diameters d₃ and d₄ are smaller than outlet portion bore diameterd₂. Accordingly, valve-inner cylinder 90 is sized to be received withinoutlet portion 54, such that cylinder 90 is substantially concentricallyaligned with respect to outlet portion 54.

A mounting flange 106 extends radially outwardly and circumferentiallyfrom cylinder outlet edge 96. Flange 106 is aligned substantiallyperpendicular to a centerline axis 108 extending through cylinder 90,and includes a plurality of fastener openings 110 that are each sized toreceive fastener 86 therethrough. More specifically, when valve-innercylinder 90 is positioned within outlet portion 54, cylinder fasteneropenings 110 are each substantially concentrically aligned with respectto each respective outlet portion flange fastener opening 84, such thatfasteners 86 extending through openings 110 and 84 secure valve-innercylinder 90 in alignment within outlet portion 54.

A valve piston 120 is slidably coupled between valve-inner cylinder 90and outlet portion 54. More specifically, valve piston 120 is asubstantially right hollow cylinder that that extends from an inlet edge124 to an outlet edge 126, and includes an exterior surface 128 and aninterior surface 130. Exterior and interior surfaces 126 and 130,respectively, define respective external and internal diameters d₅ andd₆ for piston 120. In the exemplary embodiment, diameters d₅ and d₆ aresubstantially constant between piston edges 124 and 126, and bothdiameters d₅ and d₆ are larger than valve-inner cylinder externaldiameter d₃. In an alternative embodiment, an inlet side of piston 120has a smaller diameter than an outlet side of piston 120, which asdescribed in more detail below, facilitates piston 120 being doubleacting. Additionally, piston external diameter d₅ is slightly smallerthan outlet portion bore diameter d₂, such that when piston 120 isreceived within outlet portion 54, piston external surface 128 isslidably coupled against outlet portion interior surface 70 betweenoutlet portion shoulder 78 and inlet portion 52.

A seal assembly 131 extends circumferentially around piston outlet edge126 to facilitate minimizing leakage of actuation air past piston outletedge 126. Seal assembly 131 is substantially perpendicular to acenterline axis 132 extending through cylinder 120, and has an outerdiameter d₇ that is slightly smaller than outlet portion bore diameterd₁.

Piston internal diameter d₆ is larger than valve-inner cylinder externaldiameters d₃ such that a gap 140 is defined between piston interiorsurface 130 and valve-inner cylinder external surface 98. Morespecifically, gap 140 extends between seal assembly 131 and piston inletedge 124. A valve spring 150 extends circumferentially within gap 140between valve-inner cylinder 90 and valve piston 120, and as describedin more detail below, is used to regulate operation of valve assembly14.

Valve piston 120 also includes a pair of openings 154 that are extendsdiametrically aligned with respect to valve piston 120 and extendpartially between exterior surface 128 and interior surface 130.Openings 154 are each sized to receive a connecting rod 155 that enablesvalve piston 120 to be coupled to an actuator system connector link 156.

Valve inlet portion 52 includes an interior surface 160 that extendsthrough inlet portion 52 to assembly inlet 56 and defines a portion ofassembly bore 64. In the exemplary embodiment, a diameter d₈ of inletportion 52 remains substantially constant through inlet portion 52between outlet portion 54 and assembly inlet 56, and through anintegrally formed bend 164 that is positioned between valve outletportion 54 and assembly inlet 56. In the exemplary embodiment, inletportion 52 has a generally Z-shaped bend 164 such that assembly inlet 56is substantially parallel to assembly outlet 60. In an alternativeembodiment, interior surface 160 is oriented substantially parallel toformed bend 164 to facilitate a smooth transition between adjoiningducting 12. In a further alternative embodiment, valve assembly 14includes piston 120, but valve inlet portion 52 does not include bend164. Rather, in this alternative embodiment, valve inlet portion 52 is asubstantially right cylinder.

Valve inlet portion 52 includes a centerline 170 that extends betweenassembly inlet 56 and outlet portion 54. More specifically, in theexemplary embodiment, between inlet 56 and bend 164, centerline 170 issubstantially parallel to outlet portion centerline 72, and between bend164 and outlet portion 54, centerline 170 is substantially co-linearwith outlet portion centerline 72. Accordingly, within bend 164,centerline 170 extends obliquely with respect to outlet portioncenterline 72. More specifically, within bend 164, centerline 170 isobliquely offset an angle θ from outlet portion centerline 72. In oneembodiment, angle θ is equal between approximately six and twentydegrees. In the exemplary embodiment, angle θ is approximately equalthirteen degrees.

Inlet portion diameter d₈ is smaller than bore diameter d₂ extendingbetween outlet portion shoulder 78 and inlet portion 52. Accordingly, ashoulder 182 is defined at the union of inlet and outlet portions 52 and54, respectively. Shoulder 182 provides a biasing contact for valvespring 150, and includes an annular seat 184 has a diameter d₉ that isslightly smaller than valve inner cylinder external diameter d₃, and assuch facilitates positioning valve-inner cylinder 90 with respect tovalve body 50.

Inlet portion 52 includes an opening 186 that extends diametricallythrough inlet portion 52 between inlet portion exterior surface 66 andinterior surface 160. In the exemplary embodiment, opening 186 issubstantially parallel valve piston opening 154 and is sized to receivean actuator system axle 190 therethrough. More specifically, and asdescribed in more detail below, each opening 186 extends through anactuator system inlet mount 188 that is integrally formed with inletportion 52.

An actuator system 200 is coupled to valve body 50 to facilitatecontrolling fluid flow through valve assembly 14. Specifically, actuatorsystem 200 is coupled to valve inlet and outlet portions 52 and 54,respectively, by connector link 156. More specifically, an inlet side202 of connector link 156 is coupled to axle 190 for controllingrotation of a sealing mechanism or sealing plate 206.

Sealing plate 206 has a substantially circular outer perimeter 208 and asubstantially arcuate cross-sectional profile. In the exemplaryembodiment, sealing plate 206 is formed with a constant radius such thatplate 206 has a truncated spherical cross-sectional profile. Sealingplate 206 includes a front side 210 and an opposing rear side 212. Plate206 includes a centerline axis 214 extending therethrough, and a shaftbore 216 that extends therethrough and is sized to receive axle 190therein. More specifically, axle 190 extends through shaft bore 216 andpivotally couples plate 206 within valve body 50.

Each plate side 210 and 212 defines a portion of shaft bore 216. Morespecifically, bore 216 is not concentrically aligned with respect toplate centerline axis 214, but rather extends obliquely through plate206 with respect to centerline axis 214. Accordingly, each side 210 and212 includes a raised area 218 that extends outwardly from an outersurface 220 of plate 206 in a frusto-conical cross-section to define aportion of shaft bore 216.

Plate raised areas 218 enable axle 190 to extend through plate 206within inlet portion bend 164. More specifically, axle 190 is alignedsubstantially perpendicularly with respect to outlet portion centerline72, and is therefore aligned obliquely at angle θ with respect to bendcenterline 170. Accordingly, when plate 206 is in a fully open position,as shown in FIGS. 2 and 3, plate 206 is obliquely offset with respect toinlet portion bend 164. However, because axle 190 is offset from platecenterline axis 214, when plate 206 is rotated to a fully closedposition, plate 206 is aligned substantially perpendicularly withrespect to bend centerline 170 such that plate outer perimeter 208circumferentially contacts inlet portion interior surface 160 in sealingcontact, as described in more detail below. In one embodiment, valveassembly 14 includes a sensor to sense a position of plate 206 withrespect to valve assembly, such as but not limited to an LVDTdisplacement transducer. Valve axle 190 is inclined at angle θ withrespect to bend centerline 170 and with respect to plate centerline axis214 to facilitate providing a continuous and substantially round sealingcontact between plate outer perimeter 208 and interior surface 160. Morespecifically, bend 164 enables plate 206 to be aligned substantiallyperpendicularly to interior surface 160 when plate 206 is fully closed,and causes axle 190 to be aligned substantially perpendicularly to themotion of piston 120.

Axle 190 is rotatably coupled to connector link inlet side 202 at eachactuator system inlet mount 188 by a pair of bearings 230, a valve lock232, and a pair of cranks 234. More specifically, bearings 230 arerotatably coupled to axle 190 within each mount 188, and are secured inposition by seal members 236. A seal member 236 nearest valve lock 232are coupled to inlet portion 52 by a plurality of fasteners 240 thatextend through seal member openings 242 and into integrally formed inletmount openings 244 and into integrally formed inlet mount openings 244.A seal member 236 opposite valve lock 232 are coupled to inlet portion52 by an arcuate snap ring 245. Seal members 236 facilitate preventingfluid leakage through inlet portion opening 186 and around axle 190.

Axle 190 is then inserted through each valve lock 232 prior to beingcoupled to connector link inlet side 202 by each respective crank 234.Valve lock 232 facilitates maintaining axle 190 in rotational position,such that plate 206 may be maintained in an orientation, such as fullyopen or fully closed, with respect to valve body 50.

An outlet side 250 of each connector link 156 is coupled to valve piston120 by connecting rod 155 through connector link mounts 80. Morespecifically, each connector link mount 80 includes an integrally formedslot 252 that extends substantially parallel to outlet portioncenterline 72. Each slot 252 is sized to receive a slider 254 therein inslidable contact, and includes a slotted opening 256 that extendsthrough slot 252. Each connecting rod 155 is coupled to valve piston 120and extends radially outward through slotted openings 256 and throughsliders 254 to couple through a threaded nut 258 to connector linkoutlet side 250. More specifically, a cover plate 260 is aligned withrespect to slot 252 by a plurality of dowel pins 262 that extend throughcover plate openings 266.

During operation, fluid enters valve assembly 14 through assembly inlet56 and into valve body inlet portion 52. Inlet portion bend 164 causes adirection fluid flowing within inlet portion 52 to be changed withininlet portion 52. More specifically, fluid flow is turned through angleθ in the vicinity of plate 206. Bend 164 enables axle 190 to be coupledsubstantially perpendicularly to movement of piston 120 which, asdescribed in more detail below, facilitates converting rectilinearmotion of piston 120 into rotary motion of sealing plate 206.Accordingly, if plate 206 is in a fully closed position, plate 206 issubstantially perpendicular to a direction of fluid flow within bend164. As such, plate outer perimeter 208 forms a substantially continuousseal circumferentially within inlet portion 52, which facilitatespreventing fluid flow through valve assembly 14. More specifically, whenplate 206 is rotated to the closed position, actuator or supply fluid isturned off and spring 150 biases sealing plate 206 through actuatorsystem 200 in the fully closed position.

Main actuation fluid enters valve piston 120 through a port 277 andoperates against valve piston outlet face 126. Additional actuationfluid operates on valve piston 120 in a gap 279 that is partiallydefined between valve piston inlet edge 124 and shoulder 182.Accordingly, piston 120 is double actuated by the actuation fluid. Morespecifically, when plate 206 is desired to be rotated into a partiallyopened or modulated position, main pressurized actuator fluid issupplied to outlet portion 54 through port 277 into a gap 280 definedbetween valve piston seal assembly 131 and valve-inner cylinder mountingflange 106. The fluid pressure of the actuator fluid forces piston 120to translate, which in turn causes connectors links 156 to translatethrough slots 252. The translational motion of links 156 causessubsequent rotational motion of valve cranks 234. Rotation of cranks 234causes rotation of axle 190 which causes plate 206 to rotate from theclosed position, such that fluid flows past sealing mechanism 206 anddownstream from valve assembly 14.

Annular seat 184 allows for axial thermal growth differences betweenvalve-inner cylinder 90 and valve body 50. Seat 184 also permits flidthat has flowed downstream from seat 206 to enter gap 140. Fluidpressure within gap 140 acts in opposition to the force induced byactuation fluid, which in conjunction with spring force induced byspring 150 causes plate 206 to self-regulate the flow of fluid. Morespecifically, if the downstream pressure decreases, the opposing forcealso decreases, which allows pressurized actuation fluid to forcesealing mechanism 206 to open more fully to restore the regulated fluidflow at a predetermined pressure.

Despite the offset of inlet portion 52 with respect to outlet portion54, a center of gravity 290 of valve assembly 14 is locatedsubstantially along outlet portion centerline 72. Accordingly, bendingstresses induced to valve assembly 14 during the operation of actuatorsystem 200 are facilitated to be reduced in comparison to other knownvalves which have offset centers of gravity. As such, valve body 50facilitates extending a useful life of valve assembly 14. Furthermore,because center of gravity 290 is positioned along outlet portioncenterline 72, eccentricity induced bending stresses of adjoiningducting 12 are also facilitated to be reduced, which facilitates the useof mounting bracket assemblies 42 fabricated from lighter weightmaterials. In addition, valve assembly 14 requires less physical spaceenvelopes than other known valve assemblies used for the sameapplications.

FIG. 4 is a perspective view of an alternative embodiment of a valveassembly 300 that may be used with gas turbine engine 10 (shown in FIG.1). FIG. 5 is a side view of valve assembly 300. Valve assembly 300 issubstantially similar to valve assembly 14 (shown in FIGS. 2 and 3) andcomponents of assembly 14 that are identical to components of valveassembly 300 are identified in FIGS. 4 and 5 using the same referencenumerals used in FIGS. 2 and 3. Accordingly, valve assembly 300 includesvalve body 50, inlet portion 52, and outlet portion 54. Additionallyvalve assembly 300 includes valve-inner cylinder 90, valve piston 120,and an actuator system 302. Actuator system 302 is substantially similarto actuator system 200 and includes a pair of pivot links 303 coupled tosealing plate 206 by a wishbone link 304.

More specifically, each wishbone link 304 includes a pair of outlet endsand a connector actuator coupler 312. Each wishbone link outlet end iscoupled to outlet portion 54 by connecting rods 155 extending throughmounts 80. More specifically, each wishbone link mount 80 includes slot252 and slider 254. Each connecting rod 155 is coupled to valve piston120 and extends radially outward through slotted openings 256 andthrough sliders 254 to couple through bushing 258 to pivot link outletside 250. More specifically, cover plate 260 is coupled to each pivotlink mount 80 by fasteners 262 that extend through cover plate openings266 into openings 268 formed integrally within each link mount 80.

Each pivot links 303 is pivotally coupled to wishbone link 304 betweenwishbone link outlet end 156 and wishbone connector actuator coupler312. Pivot links 303 provide additional support to wishbone link 304 andfacilitate maintaining wishbone link 304 in alignment with respect tovalve assembly 300.

Wishbone link 304 extends partially circumferentially to couple togetherwith an actuator rod 320 that extends laterally upstream towards aninlet actuator mount 188. Within valve assembly 300, inlet portion 52includes only one actuator mount 188, but also includes anintegrally-formed axle seat 322 that is described in more detail below.Each wishbone link 304 is also pivotally coupled by a hinge pin 324 thatis positioned between wishbone link outlet end 156 and wishboneconnector actuator coupler 312.

Actuator rod 320 is coupled to actuator mount 188 with an axle 190 thatis rotatably coupled to actuator rod 320 by a bearing 230, a valve lock232, a crank 234, and a yoke 330. More specifically, bearing 230 isrotatably coupled to axle 190 within mount 188, and is secured inposition by a seal member 236. Axle 190 is also inserted through valvelock 232 prior to being inserted through yoke 330 and coupled toactuator rod 320 by crank 234. Yoke 330 provides additional support toactuator system 302.

Axle 190 does not extend diametrically through inlet portion 52, butrather, an inner end 340 of axle 190 is rotatably coupled within abearing assembly 342. More specifically, bearing assembly 342 is seatedwithin axle seat 322. Accordingly, because valve assembly 300 includesonly one opening 186 within inlet portion 52, valve assembly 300facilitates reducing blow-by leakage that may occur through openings186.

The above-described valve assembly is cost-effective and highlyreliable. The valve assembly includes a valve body that includes anintegrally formed inlet and outlet portion. Because the portions areonly offset by a minimal angle, the center of gravity of the assembly islocated within the valve assembly and along a centerline of the outletportion. As such, vibrational induced bending moments and eccentricityinduced stresses to the valve body are facilitated to be reduced. As aresult, the valve body facilitates extending a useful life of the valveassembly in a cost-effective and reliable manner.

While the invention has been described in terms of various specificembodiments, those skilled in the art will recognize that the inventioncan be practiced with modification within the spirit and scope of theclaims.

1. A method for operating a gas turbine engine, said method comprising:directing fluid flow from a source into an inlet of a valve; channelingthe fluid flow entering an inlet portion of the valve towards an outletportion of the valve such that a direction of the fluid flow is changedwithin the inlet portion; controlling the amount of fluid flow enteringthe outlet portion of the valve by selectively positioning a valve diskcoupled within the inlet portion of the valve by a valve disk axle;controlling the amount of fluid flow entering the outlet portion of thevalve with a piston assembly that is translatable in a direction that issubstantially parallel to a centerline axis of symmetry of the valveoutlet portion; and channeling the fluid flow from the inlet portion ofthe valve through the outlet portion of the valve and into a fluidsupply pipe, wherein the valve outlet portion has a substantially rightcylindrical shape such that a direction of fluid entering the bodyoutlet portion remains substantially constant therethrough.
 2. A methodin accordance with claim 1 wherein controlling the amount of fluid flowentering the outlet portion of the valve further comprises controllingthe amount of fluid flow entering the outlet portion by selectivelyrotating the valve disk between an open position and a closed position,wherein the valve disk axle is substantially perpendicular to valveoutlet portion centerline axis of symmetry.
 3. A method in accordancewith claim 1 controlling the amount of fluid flow entering the outletportion of the valve further comprises controlling the amount of fluidflow entering the outlet portion using a piston assembly that is housedwithin the outlet portion and includes a biasing mechanism used to biasa relative position of the valve disk.
 4. A method in accordance withclaim 1 wherein channeling the fluid flow from the inlet portion of thevalve through the outlet portion of the valve and into a fluid supplypipe further comprises channeling fluid flow through the valve tofacilitate reducing stresses induced to the fluid supply pipe.